Generally speaking, if you are just watching content, either would work. The thing to consider is future applications. I will generally buy the biggest and baddest to be future proof but sometimes you have to consider your budget and go for the biggest bang for the buck. Especially if it does not look like anyone is going to develop applications that will use 8 cores.

I think you would be fine for the time being with the quad, but I cannot say the same would be true tomorrow.